sql server grants access to specific login to database.

Question

hello friends...
i have created website for intranet and hosted it on server. for that i needed to create login "IIS APPPOOL\hi" in sql server 2008 for my application to access my "reportdb" database. "IIS APPPOOL\hi" has sysadmin and public server roles in sql server 2008. And i had created another login "sa" same as "IIS APPPOOL\hi". these are working correctly.
Now I want these two logins to access "reportdb" for all operations in database and remaining all logins should be denied to access "reportdb". My Sql Server 2008 is having mixed mode (windows authentication and Sql authentication). plz help me